The present invention relates to a sewing machine, and more particularly, a rotary shuttle device for the sewing machine, which is formed with separated three parts that are removably coupled or assembled each other so as to be capable of facilely and conveniently repairing or replacing only a corresponding worn portion or a portion that requires replacement.
Generally, a sewing machine, as shown in FIG. 1, has a rotary shuttle device for supplying an under thread. The rotary shuttle device comprises an outer shuttle which is disposed at a driving shaft 1 rotatably connected to a power generating unit, an inner shuttle 3 which is received in the outer shuttle 2, a bobbin 4 which is received in the inner shuttle 3 and on which the under thread is wound, and a bobbin case 5 for receiving the bobbin 4. Typically, the bobbin 4 is formed with a cylindrical winding drum 6 on which the under thread is wound, and a flange portion 8, 9 which is fixed to both ends of the winding drum 6. On a bottom portion 7 of the inner shuttle 3, a stud 10 is disposed upright toward an open end side thereof. The winding drum 6 of the bobbin 4 is rotatably inserted onto the stud 10. The outer shuttle 2 has a track groove 11 formed at an inner portion thereof and a pointed end 12 formed at one end thereof. A groove 13 is formed adjacent to the pointed end 12 to have a gentle radius of curvature so that the under thread is passed through the groove 13, while being contacted with the groove 13. On an outer side of the inner shuttle 3 is formed a track portion 14 which is inserted into the track groove 11. Therefore, the inner shuttle 3 is rotatably mounted in the outer shuttle 2. Meanwhile, a semicircular guide portion 15 is fixed to one half portion of an outside portion of the outer shuttle 2 by fastening means such as a bolt so as to rotatably and removably mount the inner shuttle 3 in the outer shuttle 2. The guide portion 15 has a pointed end 16 opposite to the pointed end 12 formed at a main body of the outer shuttle 2. In addition, a bracket 18 is removably fixed to the other half portion of the outside portion of the outer shuttle 2 by the fastening means such as the bolt to be continuous with the guide portion 15. The bracket 18 has a pointed end 19 opposite to the pointed end 16 of the guide portion 15. According to a construction as described above, when a sewing device is operated, the outer and inner shuttles 2, 3 are relatively rotated, and at the same time, the under thread wound on bobbin 4 is pulled out and supplied through the groove 13 formed adjacent to the pointed end 12 of the outer shuttle 2 to a lower portion of cloth to be sewn. Then, the under thread is sewn into the cloth in cooperation with an upper thread supplied from an upper portion of the cloth.
However, there are some problems in the conventional rotary shuttle device for a sewing machine. That is, since the under thread pulled out of the bobbin 4 during the rotation of the inner shuttle 3 at high speed is passed through the groove 13 of the outer, while being contacted with the groove 13, the groove 13 is worn. In case the groove is locally worn, the under thread is caused to be broken. In the worst case, a portion of the groove 13 is cut out. In this case as well as the case that only the portion of the groove 13 is excessively worn, the outer shuttle 2 or the whole rotary shuttle device has to be replaced with new one. Therefore, there is a problem that costs a great deal. And since the inner shuttle 3 is rotated with respect to the outer shuttle 2 at the high speed, the track portion 14 formed at an outer circumference of the inner shuttle 3 wears the track groove 11. If the track groove 11 is excessively worn, the inner shuttle 3 is shaken or abnormally rotated. The under thread is broken, or the shuttle device is entirely out of order to cause sewing defect or make it impossible to perform the sewing operation. In this case, since the expensive outer shuttle or whole rotary shuttle device has to be replaced, , there is also the problem that costs a great deal.
Further, since an open space of the outer shuttle for receiving the inner shuttle is very limited and restricted and it is also very difficult to exactly insert the track portion of the inner shuttle into the track groove of the outer shuttle, there is a problem of lowering work efficiency and assembly efficiency.
Moreover, since the guide portion is essentially provided to the outers shuttle in order to insert the inner shuttle into the outer shuttle, the number of components is increased and thus the number of the fastening means such as the bolt for fastening the components is increased. Therefore, there is a problem of increasing fabrication cost as well as lowering the work-efficiency.
Therefore, it is an object of the present invention to provide a rotary shuttle device for a sewing machine, which is capable of selectively replace only an excessively worn portion or a portion that requires replacement so as to reduce maintenance cost.
It is other object of the present invention to provide a rotary shuttle device for a sewing machine, which is capable of selectively replace only a groove member of an outer shuttle or a track groove member worn by a track portion of an inner shuttle.
It is another object of the present invention to provide a rotary shuttle device for a sewing machine, which is separately formed with a main body, a groove member and a track groove member.
It is yet another object of the present invention to provide a rotary shuttle device for a sewing machine, which is capable of facilely inserting an inner shuttle into an outer shuttle.
To accomplish the above objects and advantages, there is provided a rotary shuttle device for a sewing machine, comprising an outer shuttle that is disposed at a driving shaft of a power generating unit of the sewing machine, a bobbin which is rotatably disposed in an inner shuttle so that an under thread is wound thereon, a bobbin case for receiving the bobbin and a bracket which is disposed around the outer shuttle, characterized in that, the outer shuttle comprises a main body integrally provided with a base portion which is disposed at the driving shaft, a first supporting portion which is protruded at one side of the base portion to have a first partial track groove on an inner face thereof, and a second supporting portion which is protruded at the other side of the base portion to be opposite to the first supporting portion and have a second partial track groove on an inner face thereof; a track groove member which is removably disposed between the first and second supporting portion and has a third partial track groove communicated with the first partial track groove of the first supporting portion and the second partial track groove of the second supporting portion; and a groove member which is removably fixed to the second supporting portion of the main body, and formed with a pointed end, a groove through which the under thread wound on the bobbin is passed while being contacted therewith and a fourth partial track groove communicated with the second partial track groove of the second supporting portion.